Wide-Area Protection of AC/DC Distribution Network Based on Fault Degree Correlation Matrix

The integration of the distributed generations and DC network has aggravated the complexity of fault characteristics of distribution systems, and the traditional protection strategy cannot meet the security and stability requirements of distribution systems under new conditions. In this paper, a centralized backup protection strategy which is suitable for AC/DC hybrid power grid is proposed. The scheme extracts the direction of fault current component of each IED (Intelligent Electronic Device) in the grid and obtains the corresponding fault correlation coefficient based on the fault current value. A matrix that can evaluate the severity of the fault can be obtained by combining the information above, helping the protection strategy to realize fault location and isolation. Finally, a simulation example is given to verify that the protection scheme can effectively adapt to the changes of the operation conditions with high-permeability DGs, being able to identify the fault quickly and accurately, which is of great significance for the secure and reliable operation of AC/DC hybrid system.